I think most folks that are reading this don’t have a full picture of what’s going on and I think that’s contributing to a smaller number of responses to you.

I’d want to know the rest of the details. We see what you’re talking about on the left wall and the physical location of the lineal drain. But...

If you want to stop the tile on the left wall at 4.5’, what are you covering the waterproofing membrane with?
How big are tiles inside and outside the shower pan?
How much is the floor sloped inside the pan and outside the lineal drain?
Using a level to determine this: what is the height difference between the top of the drain grate and the unsloped/flat/level part of the bathroom floor?
Are you overlapping the Kerdi inside the shower 2” onto the Ditra outside, or just abutting?
How big is the wall on the right, what’s it’s configuration, how far is it’s waterproofing, and how far is it being tiled?
Is there just one single shower head,which direction does it spray, and is a “normal” or high volume spray?

At least those are the first few questions that would help us steer you right.